Moulds are a type of fungus. Moulds spread by releasing millions of tiny spores into the air. They need moisture to grow and are usually found in damp, poorly ventilated areas of homes, such as bathrooms. You cannot see the spores but you may be able to see moulds, grey, green or black in colour, growing on damp surfaces.
Mould spores are a source of indoor air pollution. Airborne mould spores can produce allergic reactions in sensitive people similar to hay fever. People who experience allergic reaction to mould spores are also more likely to suffer from asthma.
Mould spores can be reduced by improving ventilation in the home, and by limiting sources of moisture and condensation.